This review focuses on the synthesis and reactivity of thioketone S‐oxides (sulfines). Sulfines have been long established as being reactive intermediates of high interest and with potential for wide application in organic synthesis. The review will cover many aspects of sulfines: the first section looks at the different routes to the synthesis of these compounds with a detailed look at more recently developed routes; the second section details the scope of reactivity of these types of compounds and how they are useful in synthetic organic chemistry with a particular look at cycloaddition and nucleophilic addition reactions.

Continuous-flow generation of α-diazosulfoxides results in a two-to three-fold increase in yields and decreased reaction times compared to standard batch synthesis methods. These high yielding reactions are enabled by flowing through a bed of polystyrene-supported base (PS-DBU or PS-NMe 2 ) with highly controlled residence times. This engineered solution allows the α-diazosulfoxides to be rapidly synthesized while limiting exposure of the products to basic reaction conditions, which have been found to cause rapid decomposition. In addition to improved yields, this work has the added advantage of ease of processing, increased safety profile, and scale-up potential.

Diazo transfer to β-keto sulfoxides to form stable isolable α-diazo-β-keto sulfoxides has been achieved for the first time. Both monocyclic and benzofused ketone derived β-keto sulfoxides were successfully explored as substrates for diazo transfer. Use of continuous flow leads to isolation of the desired compounds in enhanced yields relative to standard batch conditions, with short reaction times, increased safety profile, and potential to scale up.

The generation of novel 1,2,5-oxathiazole-S-oxide cycloadducts from cycloaddition of nitrile oxide dipoles with α-oxo sulfines generated in situ from α-diazosulfoxides is reported.

Review: 154 refs.